Current implantable cardiac electrotherapy leads (e.g., cardiac resynchronization therapy (CRT) leads, bradycardia therapy leads, and tachycardia therapy leads) typically include multiple cable conductors. Each of the cable conductors may be electrically connected to an electrode, shock coil, or other conductive element at some location along the lead to allow an electrical circuit to be formed in conjunction with the cardiac electrical system of a patient by way of a lead coupled to a pacemaker, defibrillator, or other cardiac therapy device.
While ongoing development of implantable cardiac electrotherapy leads has resulted in at least some newer leads which have a helically wound lead body providing improved reliability, especially with respect to reduced cable fatigue, fractures, and abrasion, other potential concerns remain, such as electrical isolation between the cable conductors and overall stiffness of the lead. More specifically, lack of electrical isolation between cable conductors may render the cardiac therapy device inoperative. In at least some cases, the possibility of unintended electrical coupling between cable conductors may be particularly pronounced at a distal end of the lead opposite the cardiac therapy device.
Further, excessive stiffness of the lead may result in reduced flexibility for those applications in which the lead may benefit from flexibility so that the attached conductive elements may reach all intended destinations in the body. Oppositely, some applications may require more strength and, consequently, less flexibility so that, for example, the lead or a conductive element attached thereto may be torqued or pushed to properly position the lead.
With the above aspects in mind, as well as others not explicitly discussed herein, various embodiments of an implantable cardiac electrotherapy lead, as well as embodiments for manufacturing such leads, are disclosed herein.